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Asked: 2019-04-04 18:41:15 +0800 CST

mysqld: Can't create/write to file '/home/mysqltmp/ibXXX' Permission denied

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My main volume is a 20GB SSD disk mounted on /. I have a 4TB HDD mounted in /home. So to save space I want to set the mysql temporary directory to /home/mysqltmp.

However when I set to this directory mysql won't start. I get error:

mysqld: Can't create/write to file '/home/mysqltmp/ibm7cVN0' (Errcode: 13 "Permission denied")

I checked the permission and it is correct:

# ls -ld /home/mysqltmp/
drwxrwxrwx 2 mysql mysql 4096 Apr  4 03:19 /home/mysqltmp/

Running mysqld as root it starts without problem.

Server:

# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.6 LTS
Release:    16.04
Codename:   xenial

Note: Problem arose after updating to 16.04, was working on 14.04

MySQL details:

# mysql -V
mysql  Ver 15.1 Distrib 10.1.38-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2
mysql

1 Answers

  1. I think this could be UMASK values. Please check umask.

    To change the default UMASK value, start mysqld_safe as follows:

    $ UMASK=384  # = 600 in octal
$ export UMASK
$ mysqld_safe &

    By default, MySQL creates database directories with an access permission value of 0750. To modify this behavior, set the UMASK_DIR variable. If you set its value, new directories are created with the combined UMASK and UMASK_DIR values. For example, to give group access to all new directories, start mysqld_safe as follows:

    $ UMASK_DIR=504  # = 770 in octal
$ export UMASK_DIR
$ mysqld_safe &
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